WIXLIB

ATM and the Internet OverSatellite NetworksPrakash ChitreCOMSAT LaboratoriesClarksburg, MD 20871(301) 428-4167e-mail: prakash.chitre@comsat.comATM & INTERNET 7/99 1

ATM and Internet Via Satellite ATM Via Satellite: Key ChallengesATM Over (Point-to-point) SatelliteLinksInternet Over (Point-to-point)Satellite LinksATM/Internet Satellite MeshNetworksConclusionsATM & INTERNET 7/99 2

ATM Via Satellite: Key Challenges Providing Fiber-like Quality (Cell Loss Ratio and Cell ErrorRatio) Time-varying bit error rates and bit error distribution Effect on Throughput Performance due to GeosynchronousSatellite Delay ATM Traffic Management, Congestion Control End-to-end protocols, e.g., TCP Efficient Bandwidth Use ATM and other ATM related protocols (such as ATM speech) arenot bandwidth efficient Satellite resources are relatively expensive Dynamic Bandwidth-on-Demand Concepts Meeting Cell Delay Variation QoS Requirements Satellite TDMA framing can result in unacceptable cell delayvariationATM & INTERNET 7/99 3

Seamless Integration of Satelliteand Terrestrial Networks Satellite link transparent to the end user Service provisioning in a cost-efficient mannerATM & INTERNET 7/99 4

Steps for AchievingSeamless IntegrationATM & INTERNET 7/99 5 Modify existing standards Develop new standards New Satcom interfaces New satellite networks

Service Specific ConnectionOriented Protocol (SSCOP) SSCOP is the basic protocol for errorrecovery in ATM Very efficient over satellite links evenat gigabits per secondATM & INTERNET 7/99 6

Communications and InteroperabilitySection/TR 34.1Major Accomplishments Established a liaison with ATM Forum Wireless ATM Group for thejoint development of satellite ATM network architectures, protocols,mobility standardsWorked closely with Internet Engineering Task Force (IETF) forinternet protocols to work well over satellite TCPSAT Group has been establishedATM traffic management (TM 4.0) Modifications to accommodate satellite delay were approved by ATM Forum ATM speech Worked with ATM Forum to develop ATM speech standards to be bandwidthefficient Common air interface for satellite systems Standardize common air interfaces for a range of satellite systems from satellitepersonal communications systems to broadband satellite systemsATM & INTERNET 7/99 7

Asynchronous Transfer Mode (ATM)over SatelliteATM & INTERNET 7/99 8

COMSAT ATM Link Accelerator - ALA Provides fiber-like quality over satellite links for ATMtraffic Improved BER (10-9 or better), very low cell loss ratio Cell header and payload protected usingpowerful FEC codes Adaptive FEC to maximize bandwidth utilization FEC overhead 0% to 8%, depending onlink quality Idle cells stripped off Interleaving to combat burst errors Can correct up to 72 octet burst errors Prioritized traffic management High priority, low jitter for CBR and VBR traffic(e.g., video) Low priority, large buffers for ABR traffic(e.g., LAN data) Lossless data compression for ABR traffic on selectedVCs Can double effective throughput Selectable T1, E1, DS-3, E3, RS-449 ATM interface Satellite interface up to 8 Mb/sATM & INTERNET 7/99 9

Cell Loss Error RatioCLA-2000/ATM Performance v/s BER1E 201E-01Without ALAWith ALA1E-021E-031E-041E-051E-061E-07Bit E rror Ra t e ( burs t y )ATM & INTERNET 7/99 101E-081E-091E-10

Example Operational NetworkUUNetBackboneMiamiCiscoRouterDS3ATMSwitch34 Mb/sPuerto Rico34 Mb/sATMSwitchDS3 Undersea CableDS3CiscoRouterALA/ALEDS3O MSCAT ALA -2 0 0C iD D spLl ayl a mrAPowerATMSwitchCOMSAT ALA- 20 0L C D si pl ayl aArmE3PowerArgentina10 Mb/sALA/ALEE3ATMSwitchC O MSAT ALA -2 0 0CDDLs pl ayl aAr mPowerC O MSAT ALA -2 0 0CDDLs pl ayl aAr mE3CiscoRouterSouth AmericanBackboneATM & INTERNET 7/99 11Power

TCP/IP Issues for Satellite Networks TCP window size Buffer requirements at end nodes and routers Slow start Effect of bit errors Retransmission strategy Congestion control strategy Queue managementATM & INTERNET 7/99 12

Maximum Throughput for SingleTCP Connection as a Functionof Window SizeATM & INTERNET 7/99 13

Current Work on TCPEnhancements ATM & INTERNET 7/99 14Random Early Discard (RED)schemeSelective Ack (SACK)Fast retransmit recoveryenhancementsSlow start enhancements

COMSAT Link Accelerator/Internet - CLA-2000/Internet IP Routing over satellite and wireless links Provides fiber-like quality over satellite links Improved BER (10-11 or better) Packets protected using powerful ReedSolomon coding Interleaving to combat burst errors Can correct 640 bit burst 490 - 4 Mbit/ sMSOCAAL20D ipClyCOAALSMA20CDi plyA lml mAo wPrwroPCOMSATCLA/IPCOMSATCLA/IP10BaseTInternet Bandwidth Expansion Adaptive Coding based on Measured Error rate Reed-Solomon coding overhead 0% - 7% Lossless Data Compression Option 2:1 compression ratio typical Up to T1 link rate RED Queue Management TCP Proxy (Spoofing) Satellite Interface, RS449, up to 4 Mbit/s symmetric Support for asymmetric rate links, low-speed linksCLA-2000/InternetClAPo wmrEthernet/IP Port10BaseTTL-0s aa reATM & INTERNET 7/99 15COMASDDilpAL Ay2 0 0Satellite/WAN PortRS-449, up to 4 Mbit/s

CLA-2000/Internet UsageCLA-2000/Internet as Router using S-4490 - 4 Mbit/ sMSOCAAL20D ipClyCOAALSMA20CDi plyA lmo wPrl RS-4490 - 4 MbpsRouterRouterCOAALSM2 0ADDCip lyOMCAASLA0 02DDCip lyl mAl mAwroPPowrCOMSATCLA-2000/InternetCLA-2000/Internet as TransparentFrame Processor using Serial PortCOMSATCLA-2000/InternetSerial Link0 - 8 MbpsInternetATM & INTERNET 7/99 16

CLA/Internet TCP-Proxy OverviewUser Workstation /ServerCLA-2000/InternetCLA-2000/InternetUser Workstation /ServerTCP ProxyTCP ProxyApplns.Applns.TCPTCPTCPTCPTCPIPIPIPIPIPSatt. LinkLayerSatt. LinkLayerEthernetTCP Window 4 - 64 kbytesEthernetTCP Window 256 kbytesMost PCs, workstations use TCP window size of 8 - 24 kbytesLimits throughput per connection over geo satellites to 128 - 384 kbpsMax. TCP window size allowed 64 kbytes (RFC 1323 enhancements allow larger sizes)TCP Proxy enables full link rate throughput per connectionCLA-2000/IP uses TCP with large windows over satellite segment (RFC 1323)Connection set-up/tear-down not spoofedATM & INTERNET 7/99 17TCPIPEthernetEthernetTCP Window 4 - 64 kbytesInternet

CLA/Internet TCP-Proxy OverviewUser Workstation /ServerCLA-2000/InternetCLA-2000/InternetTCP ProxyTCP ProxyApplns.TCPTCPIPIPEthernetSerialTCP Window 4-64 kbytesTCPTCPTCPIPIPIPSatt. LinkLayerSatt. LinkLayerTCP Window 256 kbytesInternetMost PCs, workstations use TCP window size of 8 - 24 kbytesLimits throughput per connection over geo satellites to 128 - 384 kbpsMax. TCP window size allowed 64 kbytes (RFC 1323 enhancements allow larger sizes)TCP Proxy enables full link rate throughput per connectionCLA-2000/IP uses TCP with large windows over satellite segment (RFC 1323)Connection set-up/tear-down not spoofedATM & INTERNET 7/99 18User Workstation /ServerApplns.TCPIPEthernetSerialTCP Window 4-64 kbytesInternet

CLA/Internet TCP-Proxy MechanismCLA-2000/InternetMSOCAL02AD ipClylmAwroPInternetInternet1 Data (1kbyte)2332 ms 456781234500 ms 5678AASMOCL20CDip lyCiscoA lmwroPCALSMO02Ai pDClyl mAwroPInternetAASMOCL20CDip lylmAwroPInternetInternetData (1kbyte)Ack12332 ms45678Data(1kbyte)12345678Ack 910Data (1kbyte)500 msData1 (1kbyte)2332 ms45678AckW 8 kbytesThroughput 8 kbytes/32 ms 2 MbpsW 8 kbytesThroughput 8 kbytes/500 ms 128 kbpsATM & INTERNET 7/99 19128AckAckW 8 kbytesW 128 kbytesThroughputThroughputW 8 kbytes 8 kbytes/32 ms 128 kbytes/500 msThroughput 2 Mbps 2Mbps 8 kbytes/32 ms 2 Mbps

CLA/Internet Single TCP ConnectionPerformance20001800Throughput Kbps1600CLA, r 2.048 MbpsW 8 kB140012001000Cisco, r 2.048 Mbps800W 192 kB600400Cisco, r 2048 kbps200W 8 kB01.E-091.E-081.E-071.E-061.E-051.E-04BERSingle Connection, Large Data Transfer (20 - 40 min)Sun Solaris 2.6One-way Delay 250 msATM & INTERNET 7/99 201.E-03

CLA-2000/IP PerformanceATM & INTERNET 7/99 21

ATM & INTERNET 7/99 itecnnfnPptBER 10-4WebSiteWorWdindows.exeUnix.exeThroughput Gain tTCPCLA/Internet CompressionMeasurements3BER 10-821.510.50

Linkway 2000 Multiservice Platform for Bandwidth-on-Demand Multimediaapplications Multicarrier, Multirate, TDMA Mesh Network ATM, IP, Frame Relay, ISDN, SS7 Interfaces Internet Routing (RIP, OSPF, BGP) Automatic Adaptive Bandwidth Assignment Various Terminal Sizes in a Single Interoperable Network Highly Integrated Board Including Modem in the Indoor UnitATM & INTERNET 7/99 23

LINKWAY OverviewOn Demand High Speed Access for Virtual Private Networks Multinational Corporate NetworksATM & INTERNET 7/99 24 Multimedia & Video Teleconferencing Internet Service Providers

Bandwidth Management Fixed Bandwidth Allocation Dynamic Bandwidth AllocationATM & INTERNET 7/99 25

Dynamic Bandwidth AllocationAlgorithm Adaptive to Traffic Changes Fair AssignmentATM & INTERNET 7/99 26

Internet Routing Protocols Routing Information Protocol (RIP) Open Shortest Path First (OSPF) Border Gateway Protocol (BGP)ATM & INTERNET 7/99 27

ConclusionsNew generation of satellite link and networkingproducts from COMSAT: Provides high quality ATM and Internet Servicesover satellite links Provides efficient use of satellite bandwidth Meets customer demandsATM & INTERNET 7/99 28

Cisco Router ATM Switch 34 Mb/s Cisco Router ATM Switch Cisco Router ATM Switch ALA/ALE ALA/ALE ATM . l Support for asymmetric rate links, low-speed links Satellite/WAN Port RS-449, up to 4 Mbit/s . Internet Routing Protocols n Routing Information Protocol (RIP) n Open Shortest Path First (OSPF)